One of the problems encountered in checking out large systems such as space vehicles prior to a launch is that many measurements have to be taken in a relatively short period of time. This requires the transmission of signals to and receiving signals from the space vehicle. For the support of a space vehicle, there may be as many as 60,000 measurements from numerous tests that have to be performed prior to and during the launch of the space vehicle. In order to transmit the information from the space vehicle to control centers, the information is normally sent in the form of telemetary links which contain, in one particular instance, approximately 2400 measurements. These links are pulse coded modulated signals that once received at the control center must be decoded by a decommutator to identifyable measurements such as temperatures, pressures, fuel levels, vibration signals, etc.
In order to decode these links of pulse coded modulator signals, PCM patchboards in conjunction with decommutators are utilized. These patchboards are usually constructed of a plurality of holes defined by electrically conductive sleeves aligned in rows and columns. The particular manner in which it is patched for decoding the information includes physically connecting wires from one particular hole to another hole. On the backside of the patchboard, there are pins corresponding in number and location to the holes on the front side and being electrically connected thereto.
Normally, the program for the decommutator is made up many months in advance of the actual launch of the space vehicle and often the information patched in the patchboard will be altered either by accidentally bumping a lead or physical deterioration. If, prior to the launch of the space vehicle a patchboard is damaged, it would cause data to be processed erroneously or not processed at all. Malfunction of any one lead on a particular patchboard could possibly delay the launch of a space vehicle for an extended period of time.
As can be seen, it is critical that the patchboards utilized in the decommutators be verified prior to proceeding into the actual launch phase. Heretofore, this required many man hours in physically checking the terminals of the patchboard according to the program.
In U.S. Pat. No. 3,705,349, there is disclosed a computer controlled wiring network test system wherein the terminals on a panel are scanned under control of a computer for establishing the connections between the particular terminals.
In U.S. Pat. No. 3,878,405, there is disclosed switching circuitry for logical testing of network connections that utilize logic circuits for testing the continuity between buses. Similar circuits are disclosed in U.S. Pat. Nos. 3,500,457 and 3,665,299.